Potassium Iodide – A Protective Measure Not a Magic Pill

Patricia Milligan
Senior Level Advisor

refresh leafOne of the protective measures that communities around nuclear power plants might use in the case of a radiological emergency is potassium iodide. But potassium iodide, often just called by its chemical symbol, KI, can be confusing for the public — exactly what does it do and when should it be taken?

So here are some facts about KI:

  • It is not an “anti radiation” pill. Potassium iodide is a salt, similar to table salt. It is routinely added to table salt to make it “iodized.” Potassium iodide, if taken within the appropriate time and at the appropriate dosage prevents the thyroid gland from taking in radioactive iodide. This can help to reduce the risk from thyroid disease, including cancer as a result of a severe reactor accident. KI doesn’t protect the thyroid gland from any other radioactive element nor does it protect the thyroid or the whole body from external exposure to radiation. Its use is very limited.
  • KI comes as a tablet, either in 65 mg or 130 mg strengths, and dose is administered according to age and/or weight. It is very important that FDA dosing guidelines be followed when taking or administering KI. Too much stable iodide in the form of KI can be harmful to small children. A tablet can be easily divided, crushed and mixed with liquid to make it easier to swallow for infants, small children and those who have difficulty swallowing.
  • It is important that KI not be taken unless directed by appropriate state or local authorities during the emergency and then, it should be taken in accordance with those directions.
  • KI is NOT the same thing as table salt, and table salt should never be ingested as a substitute.
  • The NRC provides KI – free of charge — to states that have requested it for their population within the 10-mile emergency planning zone of a nuclear power plant. Some states have distributed KI to residents of a plant’s emergency planning zone. In other states, KI is stockpiled and would be distributed if and when it is necessary.
  • In the event of a serious nuclear incident, KI could be used in addition to evacuation or sheltering in place in accordance with directions from responsible state/local officials. For more information, see Consideration of Potassium Iodide in Emergency Planning.

The FDA’s Frequently Asked Questions on KI is a very good resource if you want more information.

REFRESH is an occasional series where we revisit previous blog posts. This one originally ran in June 2012.

REFRESH: Do Not Fear Your Smoke Detector – It Could Save Your Life

Maureen Conley
Public Affairs Officer

refresh leafWe sometimes get calls from people worried about radiation from smoke detectors in their homes. There are many reasons why the public need not fear these products.

Ionization chamber smoke detectors contain very small amounts of nuclear material. They might use americium-241, radium-226 or nickel-63. These products detect fires early and can save lives. [We explained how smoke detectors work in greater detail in an earlier blog post.]

The Atomic Energy Commission granted the first license to distribute smoke detectors in 1963. These early models were used mainly in factories, public buildings and warehouses. In 1969, the AEC allowed homeowners to use smoke detectors without the need for a license. Their use in homes expanded in the early 1970s. The NRC took over from the AEC in 1975.

Makers and distributors of smoke detectors must get a license from the NRC. They must show that the smoke detector meets our health, safety and labeling requirements.

smokedetectornewMost smoke detectors sold today use 1 microcurie or less of Am-241. They are very safe. A 2001 study found people living in a home with two of these units receive less than 0.002 millirems of radiation dose each year. That is about the dose from space and the earth that an East Coast resident receives in 12 hours. Denver residents receive that dose in about three hours. These doses are part of what is known as “background radiation.”

The radioactive source in the smoke detector is between two layers of metal and sealed inside the ionization chamber. The seal can only be broken by the deliberate use of force, which obviously we discourage. Still, even then it would result in only a small radiation dose. The foil does not break down over time. In a fire, the source would release less than 0.1 percent of its radioactivity. It’s important to understand that none of the sources used in smoke detectors can make anything else radioactive.

What about disposing of smoke detectors? A 1979 analysis looked at the annual dose from normal use and disposal of Am-241 smoke detectors. The study used actual data and assumptions that would overstate the risk. It allowed the NRC to conclude that 10 million unwanted smoke detectors each year can be safely put in the trash.

The 2001 study looked at doses from misuse. It found that a teacher who removed an americium source from a smoke detector and stored it in the classroom could receive 0.009 millirems per year. If the teacher used the source in classroom demonstrations, handling it for 10 hours each year would give less than a 0.001 mrem dose. A person who swallowed the source would receive a 600 mrem dose while it was passing through the body.

I hope this information allays concerns. Unless you remove and swallow the source, your dose from a smoke detector could not be distinguished from what you get throughout your day. And that smoke detector could save your life.

 REFRESH is an occasional series during which we revisit previous blog posts. This originally ran on June 11, 2013. We are rerunning now in honor of Fire Prevention Week. According to the National Fire Protection Association, the week was established to commemorate the Great Chicago Fire, which killed more than 250 people, left 100,000 homeless, destroyed more than 17,400 structures and burned more than 2,000 acres. This year’s theme is Smoke Alarms Save Lives: Test Yours Every Month.

 

NRC Science 101: Understanding Ionizing Radiation – It’s Not That Bohr-ing!

Harry Anagnostopoulos
Health Physicist
 

science_101_squeakychalkIn this post, we will be discussing ionizing radiation. But to do that, we first have to talk about radiation, in general, and then build up to the concept of ionization.

In previous NRC Science 101 posts, we’ve talked about the composition of an atom, including electrons, protons and neutrons. In 1913, physicist Niels Bohr made adjustments to an earlier model which imagined that the structure of an atom was similar to a solar system: electrons in circular orbits around a “sun” otherwise known as an atomic nucleus.

While modern atomic science has a more accurate understanding of the atom, Bohr’s model is still useful. It is easy to visualize and helps us to think about the relationship between electrons and energy. So, for the purposes of this post, let’s use Bohr’s atomic model.

Radiation is simply the transfer of energy through a medium. The medium can be anything: water, air or even the vacuum of outer-space. The transfer of energy can be carried out by particles or by electromagnetic waves.

Let’s conduct a small experiment. Imagine putting your face close to (but not touching) a bare 100-watt light bulb in a lamp. If you did this, and closed your eyes, could you still tell if the light was on? Could you feel the heat on your face, even though you are not touching the bulb?

Of course you could. That’s radiation! Light, heat, pressure waves in the air (sound), radio signals, and x-rays are all forms of radiation.

atom2As noted in prior NRC Science 101 posts, the core of an atom (the nucleus) is surrounded by orbiting electrons, like planets or comets around a sun. The number of electrons (each with one negative electric charge) usually equals the number of positive charges in the center (from an equal number of protons). These charges cancel out. However, if an orbiting electron is pushed out of its orbit (due to it absorbing energy from an outside source), the charges are now unequal.

The result? An “ion pair” has been formed. The creation of an “ion pair” is called . . . ionization.

Ionizing radiation is radiation with enough energy to create ion pairs in atoms. It is ionizing radiation that is of particular interest to the NRC because of its potential to cause health effects (as will be discussed in a future post).

cometearthTo help you visualize this, think again about Bohr’s model. Imagine a comet (standing in place of an electron) passing through our solar system. As the comet approaches the sun, it feels an intensifying push as light from the sun imparts more and more energy to the comet. Eventually, there is so much “push” that the comet either changes speed or changes direction. Now where will it go? Will it now be on course to strike a planet or will it veer out of our solar system? It’s exactly what could happen to an electron in the subatomic universe it occupies.

But this example is nothing compared to the bizarre realm of atomic physics where a solar system (an atom) might spit out a mini-version of itself, split into two, or where two twin comets (electrons) might appear out of nothing! And there’s more! However, you will have to wait until a later post.